Androgen and its receptor AR, which is a member of the human nuclear receptor (NRs) superfamily, play critical roles in prostate cancer (PC) and castrate resistant prostate cancer (CRPC) that kills thousands of people world-wide. We posit that a better understanding of NR signaling pathway and its integration in epigenomic signaling are keys for development of future therapeutics of this deadly disease. The long term goal of our research is to discover novel components of NR function in transcriptional and epigenomic regulation with strong translational implications in human diseases. The protein kinase termed PKN1 plays a critical role in AR dependent gene regulation by establishing an epigenomic marking (histone H3 threonine 11 phosphorylation (H3T11P)) on nucleosomes at AR target genes. We hypothesize that the PKN1-H3T11P- WDR5 signaling module plays a previously unrealized and critical role in castrate resistant prostate cancer (CRPC). The goal of this present work is to perform in depth and integrative mechanistic, genome-wide, cellular and animal based studies to dissect the role of this newly discovered signaling module in AR function in CRPC. To achieve our research goals, we will utilize interdisciplinary knowledge and complementary expertise of the co-investigators spanning biochemistry, patho-physiology, genome biology, animal and cellular models of PC and molecular biology. In Specific Aims, we will examine in extensive molecular details the role of WDR5, and PKN1 in gene regulation, and CRPC-cell function in vitro and in vivo using cell and animal based models. We will also determine the gene-specific and genome-wide localization profiles of WDR5 and H3T11P in CRPC cells. Epigenomic markings and identification of their effector proteins in hormone action are new and rapidly evolving concepts and we believe our work lies at the limit of current knowledge of hormone signaling. Our findings will thus significantly advance the field by providing a better understanding of the role of epigenomic modifications and their effector proteins in nuclear receptor action and in human diseases including CRPC.